Vertical Axis Wind Turbine

ABSTRACT

An improved vertical axis wind turbine for generating electric power which includes blades that provide improved performance per unit of surface area. The blades are adapted to rotate about a vertical axis and are shaped having a leading cupped section joined to a lagging airfoil section. The leading cup section is defined by a cup radius r and the lagging airfoil section is defined by an airfoil chord length C L . The leading cupped section and lagging airfoil section extend vertically a distance h between terminal bottom and top ends. The cup radius r and chord length C L  both decrease towards the terminal bottom and top ends of the blade. Also, the airfoil section is located a radial distance C d  from the vertical axis and the radial distance C d  decreases towards the terminal bottom and top ends of the blade.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority under 35 U.S.C. 119(e) of U.S.provisional patent application Ser. No. 62/809,217 filed on Feb. 22,2019 entitled Vertical Axis Wind Turbine Blade and Illuminated OrnamentPowered by a Vertical Axis Wind Turbine, the disclosure of which ishereby incorporated herein by reference.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates generally to a wind powered vertical axiswind turbine and an illuminated ornament which utilizes a vertical axiswind turbine to charge a rechargeable battery. Energy stored in thebattery is used to illuminate a decorative ornament at night. Thepresent invention is also directed to a curved blade design for avertical axis wind turbine which provides improved performance relativeto traditional straight blades per unit of surface area.

2. Background

Decorative devices that move in the wind, often referred to as windsculptures or wind spinners, are popular as lawn decorations. During theday, if it is windy, they provide a colorful moving display. Some alsoinclude a generator or alternator that illuminates light emitting diodes(LED's) at night when the device is spinning in the wind.

Vertical axis wind turbines (VAWT) lend themselves well to decorativelawn ornaments since the blades rotate at a fixed distance from acentral vertical axis. The volume enclosed within the rotating bladesprovides a convenient and attractive location for an illuminateddecorative ornament and the alternator and electronics needed to chargea battery and control the LED illumination. It is desirable that theblades used in a VAWT operate in both drag and lift modes. Drag modeoperation allows power generation in light wind and insures that theVAWT is self-starting in almost all wind conditions. Lift mode operationat higher wind speeds optimizes power generation by increasing the tipspeed ratio (TSR) which is the ratio between the tangential speed of thetip of the blade to the actual speed of the wind. The blade shapestypically used for VAWT's that combine drag and lift mode are lacking inaesthetic qualities and do not provide optimum performance. Thereforethere is a need for a combined drag/lift mode VAWT blade design withimproved aesthetics and performance.

SUMMARY OF THE INVENTION

The present invention overcomes disadvantages of prior combineddrag/lift mode VAWT blade designs intended to be used with anilluminated ornament located within a volume enclosed by the rotatingblades.

One object of the invention is to provide a combined drag/lift mode VAWTblade design that produces more power per unit surface area of theblade.

Another object of the invention is to provide a combined drag/lift modeVAWT blade design that increases the area under the curve on a plot offull-system power (Cp) versus wind tip speed ratio (TSR) to improvesystem performance while the turbine revolutions per minute (RPM) islagging behind changing wind speeds.

Another object of the invention, is to provide a combined drag/lift modeVAWT blade design with increased hysteresis in the power transfer curveas load impedance is increased compared to as load impedance isdecreased in order to improve performance in variable wind conditions.

Another object of the invention is to provide a control system thatensures that the system operating point is on the optimum portion of thehysteresis curve.

Another object of the invention is to provide a combined drag/lift modeVAWT blade design that minimizes turbulence and noise at the blade ends.

Another object of the invention is to provide a combined drag/lift modeVAWT blade design that causes specular reflections from sunlight atmultiple elevations during the day to reach the eye of an observer.

Another object of the invention is to provide a combined drag/lift modeVAWT blade design that is self-starting.

Another object of the invention is to provide a combined drag/lift modeVAWT blade design that spins freely in winds that are too slow to createuseful power output but are fast enough to create a pleasing visualexperience.

Another object of the invention is to provide a VAWT with an alternatorconsisting of a rotor with a self-contained stator, where the rotor isattached to multiple blades at a centralized location and includes anilluminated ornament within the blades and in close proximity to therotor.

Another object of the invention is to provide VAWT with a stator thatattaches to a shaft with a terminal end that is mounted to a decorativeassembly that includes a light emitting diode (LED) for illumination, abattery to store energy derived from the wind, electronics to controlthe charging of the battery and the illumination of the LED, allenclosed within a decorative ornament that is illuminated by the LED.

In one form thereof, the present invention is directed to a verticalaxis wind turbine comprising a plurality of blades adapted to rotateabout a vertical axis, wherein each of the blades comprise: a leadingcupped section joined to a lagging airfoil section, wherein the leadingcup section is defined by a cup radius r and the lagging airfoil sectionis defined by an airfoil chord length C_(L); wherein the leading cuppedsection and lagging airfoil section extend vertically a distance hbetween terminal bottom and top ends; and, wherein the cup radius r andchord length C_(L) both decrease towards the terminal bottom and topends of the blade.

Preferably, the cup radius r and chord length C_(L) both decreasetowards the terminal bottom and top ends of the blade starting from avertical midpoint between the terminal bottom and top ends. Alsopreferably, the airfoil section is located a radial distance C_(d) fromthe vertical axis and wherein the radial distance C_(d) decreasestowards the terminal bottom and top ends of the blade starting form avertical midpoint between the terminal bottom and top ends.

More preferably, the airfoil section is located a radial distance C_(d)from the vertical axis and wherein the radial distance C_(d) decreasestowards the terminal bottom and top ends of the blade.

The leading cupped section can extend between an outermost edge and aninner area, wherein the inner area is joined with the airfoil sectionand the outermost edge traverses along an arcuate path defined by adiameter D as the blades rotate about the vertical axis and, preferably,r/D<C_(L)/D<1.

The blades can be coupled to an alternator adapted to produce electricpower. Also, the blades can be formed of sheet material. A lightemitting device can be centrally located between the plurality of bladesand can be powered by the alternator. The blades can be secured to eachother at their terminal bottom ends.

Preferably, the blades are coupled to an alternator adapted to produceelectric power and the alternator is selectively connectable to a loadthrough a load switch and further wherein, when an output of thealternator is insufficient to produce useful power, the load isdisconnected from the alternator and, after the blades and alternatorgain momentum, the load is again connected to the alternator.

The blades can be coupled to a rotor of an alternator adapted to produceelectric power, wherein the blades are attached to the rotor below avertical midpoint between the bottom and top terminal ends of the bladesand wherein the blades are secured to each other at their terminalbottom end.

In another form thereof, the present invention is directed to a verticalaxis wind turbine comprising a plurality of blades adapted to rotateabout a vertical axis, wherein each of the blades comprise: a leadingcupped section joined to a lagging airfoil section, wherein the leadingcup section is defined by a cup radius r and the lagging airfoil sectionis defined by an airfoil chord length C_(L); wherein the leading cuppedsection and lagging airfoil section extend vertically a distance hbetween terminal bottom and top ends; and, wherein the airfoil sectionis located a radial distance C_(d) from the vertical axis and whereinthe radial distance C_(d) decreases towards the terminal bottom and topends of the blade. Preferably, the radial distance C_(d) decreasestowards the terminal bottom and top ends of the blade starting form avertical midpoint between the terminal bottom and top ends.

BRIEF DESCRIPTION OF THE DRAWINGS

The above mentioned and other features and objects of this invention,and the manner of attaining them, will become more apparent and theinvention itself will be better understood by reference to the followingdescription of the embodiments of the invention taken in conjunctionwith the accompanying drawings, wherein:

FIG. 1 shows an embodiment of a wind powered alternator and anembodiment of a decorative ornament which are constructed in accordancewith the principles of the present invention;

FIG. 2 shows a simplified schematic drawing of a wind powered alternatorwith simplified blades;

FIG. 3 is a simplified version of the wind powered alternator of FIG. 1with the decorative lighting removed;

FIG. 4 shows a cross section of the structure of the blades in FIG. 3taken along line 4-4 of FIG. 3 at the vertical midpoint of the blades;

FIG. 5 shows the blades as in FIG. 4 with the addition of wind vectorsto help explain the operation of the wind powered alternator;

FIG. 6 illustrates the transitions that occur between lift and dragdominated regions of operation from a test of the wind poweredalternator shown in FIG. 1;

FIG. 7 shows output power data from the same test of the wind poweredalternator of FIG. 1;

FIG. 8 shows a wind powered alternator with the simplified rotor as inFIG. 3 using traditional Lenz style blades together with a chart thatdetails the blade parameters at elevations above and below the verticalmidpoint of the blades;

FIG. 9 shows a wind powered alternator with the simplified rotor as inFIG. 3 using one embodiment of the current invention together with achart that details the blade parameters at elevations above and belowthe vertical midpoint of the blades;

FIG. 10 shows a wind powered alternator with the simplified rotor as inFIG. 3 using a preferred embodiment of the current invention togetherwith a chart that details the blade parameters at elevations above andbelow the vertical midpoint of the blades;

FIG. 11 is a graph comparing full-system power coefficient (Cp) versustip speed ratio (TSR) for the embodiment of the invention shown in FIG.9 versus the blades shown in FIG. 8;

FIG. 12 is a graph comparing Cp versus TSR for the embodiment of theinvention shown in FIG. 10 versus the blades shown in FIG. 8;

FIG. 13 shows the output power of the blades shown in FIG. 8 compared tothe blades shown in FIG. 9 versus load resistance;

FIG. 14 shows the output power of the blades shown in FIG. 8 compared tothe blades shown in FIG. 10 versus load resistance;

FIG. 15 repeats the power versus load impedance curve for the blades asshown in FIG. 10 and illustrates a method to maintain the optimumoperating point;

FIG. 16 is a simplified schematic illustrating the use of a wind poweredalternator to charge a rechargeable battery;

FIG. 17a illustrates the specular reflection of a traditional Lenz styleblades turbine;

FIG. 17b illustrates the improved specular reflection of the preferredembodiment of the invention;

FIG. 18 shows a cut-away view of the preferred embodiment of FIG. 1;

FIG. 19 shows a cross section view of the stationary parts of thepreferred embodiment of FIG. 1;

FIG. 19b shows a cross section of ornament platform connection to thetop of the alternator shaft;

FIG. 20 is an upper view of the ornament mounting assembly with thedecorative ornament and the printed circuit board (PCB) removed;

FIG. 21 is an exploded view of the stationary parts of the preferredembodiment of FIG. 1;

FIG. 22 is a perspective view of a wind turbine blade embodying the newdesign along with additional wind turbine blades on a vertical axis windturbine and powering the centrally located globe light;

FIG. 23 is another perspective view of the wind turbine blade shown inFIG. 1 but wherein the blade is shown rotated about the vertical axiswind turbine to a different position from the position shown in FIG. 22;

FIG. 24 is a front elevation view of the wind turbine blade shown inFIG. 22;

FIG. 25 is a rear elevation view of the wind turbine blade in FIG. 22;

FIG. 26 is a right side elevation view of wind turbine blade shown inFIG. 22;

FIG. 27 is a left side elevation view of the wind turbine blade shown inFIG. 22;

FIG. 28 is top plan view of the wind turbine blade shown in FIG. 22;

FIG. 29 is a bottom plan view of the wind turbine blade shown in FIG.22;

FIG. 30 is a cross section view taken along line 30-30 of FIG. 24;

FIG. 31 is a cross section view taken along line 31-31 of FIG. 24;

FIG. 32 is a cross section view taken along line 32-32 of FIG. 24;

FIG. 33 is a cross section view taken along line 33-33 of FIG. 24;

FIG. 34 is a cross section view taken along line 34-34 of FIG. 24;

FIG. 35 is a cross section view taken along line 35-35 of FIG. 24;

FIG. 36 is a cross section view taken along line 36-36 of FIG. 24;

FIG. 37 is a cross section view taken along line 37-37 of FIG. 24;

FIG. 38 is an front elevation view of the vertical axis wind turbine andornamental light globe shown in FIG. 1;

FIG. 39 is a cross section view taken along line 39-39 of FIG. 38;

FIG. 40 is a cross section view taken along line 40-40 of FIG. 38;

FIG. 41 is a cross section view taken along line 41-41 of FIG. 38;

FIG. 42 is a cross section view taken along line 42-42 of FIG. 38;

FIG. 43 is a cross section view taken along line 43-43 of FIG. 38;

FIG. 44 is a cross section view taken along line 44-44 of FIG. 38; and,

FIG. 45 is a cross section view taken along line 45-45 of FIG. 38.

Corresponding reference characters indicate corresponding partsthroughout several views. Although the exemplification set out hereinillustrates embodiments of the invention, in several forms, theembodiments disclosed below are not intended to be exhaustive or to beconstrued as limiting the scope of the invention to the precise formsdisclosed.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows a preferred embodiment of a wind powered alternator (4)intended for powering decorative lighting such a decorative ornament(6). Three blades, also sometimes referred to as wings, (1 thru 3) causethe rotor (5) of the alternator (4) to rotate in the wind. The rotor (5)is permanently attached to blades 1 thru 3 and the stator (85) ispermanently attached to a shaft (81). The rotor (5) includes eightinternal magnets (90), with four of the magnets secured to a lowermagnet holder (84) and four of the magnets secured to an upper magnetholder (86). The shaft (81) passes through alternator (4) and isrotatably coupled to the rotor (5) by two bearings (92) that allow therotor (5) and the lower and upper magnet holders (84), (86) to rotateabout the shaft (81). The stator (85) comprises four coils of wire (93)and is sandwiched between the rotor magnet holders (84), (86). The shaft(81) attaches to a mounting stake (46). A stabilizer (47) preventscentripetal forces from spreading the blade ends during high winds.

In a preferred embodiment, the decorative ornament (6) is centrallylocated within the blades (1) (2) (3) and occupies a large portion ofthe volume within the blades so that, aside from the blades, thedecorative ornament is the dominant visual feature. In the case wherethe decorative ornament is essentially a sphere, this means the diameterof the sphere should be 30% or more of the diameter of a circle thatwould inscribe the blades at their maximum horizontal cross section. Fornon-spherical decorative ornaments, the diameter of a circle thatinscribes the maximum horizontal cross section of the decorativeornament should be 30% or more of the diameter of a circle that wouldinscribe the blades at their maximum horizontal cross section. Thealternator (4) is mounted directly below the decorative ornament (6) tohelp conceal the alternator and make the ornament (6) the dominantfeature within the spinning blades (1) (2) (3). The rotor (5) positionsthe blades such that they are very close to the decorative ornament (6)which helps conceal the rotor (6) and helps insure that the dominantvisual features are the blades and the decorative ornament.

The blades (1 thru 3) spin the rotor (5) to create an electromotiveforce (EMF) and induce an electric current/electric power in the coils(93) as those skilled in the art will understand. The faster thealternator rotor (5) rotates, the stronger is the EMF produced. Thedecorative ornament (6) sits within the blades (1) (2) (3) and isilluminated at night by an LED (95). A rechargeable battery (96) withinthe decorative ornament (6) is charged by the alternator (4) when theblades rotate and provides power for the LED (95). An electronic circuit(94) optimizes the charging of the battery (96) and controls theillumination of the LED (95).

FIG. 2 shows a simplified schematic drawing of a wind powered turbinewith simplified blades (7 thru 9) at radial distance R1 from the centerof rotation. An alternator (not shown in FIG. 2) is attached to shaft(14). Vectors (10 thru 13) represent the direction and speed of the windand are assumed to be equal. As those skilled in the art willunderstand, the concave section of blade (8) interacting with windvector (10) will produce more torque than the non-concave sections ofblades (7) and (8) interacting with wind vectors (12) and (13). Thiswill result in clockwise rotation around shaft (14). When blade (8) ismoving in line with the wind vector (10), its tangential velocity willbe some fraction of the wind speed. This fraction is known as the tipspeed ratio or TSR. This tangential velocity results in an angularvelocity W that is inversely proportional to the radial distance R1 ofthe blade from the center of rotation. As those skilled in the art willunderstand, for an unloaded alternator the TSR will remain relativelyconstant as the radial distance R1 is decreased. The result is that theEMF produced by the alternator increases in inverse proportion todecreases in radial distance R1. For an alternator that is driving aload, the TSR will decrease as the radial distance R1 is reduced due toa reduction in available torque. However, for a lightly loadedalternator, the reduction in TSR is more than offset by the increase inangular velocity W. All alternators in the following discussions areassumed to be lightly loaded. The result is that for a given wind speed,more power will be produced by blades that are closer to the center ofrotation. There is, however, a drawback to moving the blades too closethe center of rotation. If the blades are initially stationary, theinertia and friction of the system must be overcome to initiaterotation. Referring again to FIG. 2 and assuming the blades are notinitially rotating, the torque produced by the concave section of blade(8) is opposed by the torque on blades (7) and (9). The resultant torqueis the difference between torque on blade (8) and torques on blades (7)and (9). Since these torques are all directly proportional to the radialdistance of the blades from the center of rotation, the differentialtorque applied to the stationary system will be greater if the radialdistance R1 is greater. This means that it will take less wind toovercome the inertia and friction of the system if the blades arefurther from the center of rotation. Therefore, there is a tradeoffbetween keeping the radial distance of the blades R1 great enough thatthe inertia and friction of the system is overcome in light winds, andthe desire to reduce the radial distance R1 to maximize the produced EMFwhile the alternator is spinning.

To simplify further discussions, FIG. 3 is a simplified version of FIG.1 where the decorative ornament (6) and the alternator (4) have beenreplaced with a simple shaft/axis of rotation (18) that is connected tosimple rotor (17) by a bearing (48). Rotor (17) attaches to the blades(1) (2) (3) and can rotate about shaft (18).

The shape of the blades (1), (2) and (3) is shown in FIG. 4 and FIGS.22-45. FIG. 4 shows a cross section (generally designated by the numeral(45)) of the structure in FIG. 3 taken at the vertical midpoint of theblades (1), (2) and (3). The blades are assumed to be made from thinsheet metal or plastic and are shown as simple lines in the figure,although in reality they would have some thickness. Those familiar withthe art will recognize that the shape of each blade cross section is ofa form that is somewhat similar to that which is typically used in aLenz type vertical axis wind turbine. However, the characteristics ofthe sheet material shape of present blades (1), (2) and (3), as seen inthe cross section of FIG. 4, can be defined by: a leading cupped/arcuateshaped section 130 extending between an outermost edge 131 and an innerarea 132 and defined by a cup radius r; and, an airfoil section 133joined, preferably integrally, with the leading cupped section 130 atthe cup section inner area 132 and extending perpendicular to thevertical axis of rotation 18 to a lagging/back edge 134 a chord lengthdistance C_(L). The leading cupped section 130 thereby defines anarcuate leading face surface 135 and a lagging pocket 136. The cupradius r and the chord length C_(L), in turn, can be defined asfractions of the diameter D of an imaginary circle/arcuate path or plane137 that encloses the cross section of the three blades (1) (2) and (3).The leading cupped section outermost edges 131 of each of the blades(1), (2) and (3) travel along the imaginary circle/arcuate path or plane137 as the blades rotate about the vertical axis/shaft 18. In the mostgeneral of terms, these relationships can be described by:r/D<C_(L)/D<1. These ratios and the attack angle θ (the angle between anoutermost edge plane 38 which is coplanar with the vertical axis/shaft18 and the outermost edge 131 of the leading cupped section 130, and anairfoil section plane 139 which is coplanar with the vertical axis/shaft18 and is perpendicular to the airfoil section 133), along with thedistance of the radial chord length C_(d) (the radial distance of theairfoil section plane 139 from the vertical axis/shaft 18 to the airfoil133)), completely define the blade shape and their positions at anyparticular elevation along the vertical length/height h of each of theblades (1), (2) and (3). In a preferred embodiment of the invention,these ratios at the vertical midpoint of the blade would be given by:r_(m)/D_(m)=0.10; C_(Lm)/D_(m)=0.38; with θ=7.5°, C_(d)=53.5 mm, andD=181.3 mm, where the subscript m indicates the cross section at thevertical midpoint of the blades.

FIG. 5 shows the blades as in FIG. 4 with the addition of wind vectorsto help explain the operation of the present wind powered alternator. Itis assumed the blades (1), (2), and (3) are rotating clockwise aroundshaft (18) as indicated by arrow (23). The wind is represented by twoequal vectors (24) and (25). At each blade, the rotation (23) results inan airspeed due to rotation that is tangent to the direction of theblade at that location. For blade (3), the airspeed due to rotation isindicated by vector (26). For blade (2), the airspeed due to rotation isindicated by vector (27). Vectors (26) and (27) have equal magnitudes.Referring now to blade (2), the addition of vectors (25) and (27) definea resultant air flow (29). The resultant air flow (29) has a magnitudethat is less than the magnitude of the wind vector (25) and produces adrag force (30) which causes blade (2) to rotate clockwise around centerof rotation (31). Referring now to blade (3), the addition of vectors(24) and (26) define a resultant air flow (28). The resultant air flow(28) has a magnitude that is greater than the magnitude of the windvector (25) and has a positive angle of attack relative to blade (3). Asthose skilled in the art will recognize, this produces a lift force (32)which causes blade (3) to rotate clockwise around center of rotation(31). As the magnitude of resultant air flow (28) is greater than themagnitude of wind speed (24), wind turbines that use this principle canachieve TSB's greater than one. It is the same principle that allowssailboats to achieve speeds greater than the wind speed when they aretacking and is often likened to the sail (or blade) creating its ownwind.

Referring again to FIG. 5, it can be seen that at low RPM's, theairspeed due to rotation vector (23) will be small and the resultant airflow (28) will be nearly equivalent to the wind vector (24). Under theseconditions, the lift force (32) will be small. At blade (2) theresultant air flow vector (29) will also be nearly equivalent to windvector (25), but in this case vector (29) will be near its maximum valueresulting in a large drag force (30). Under these conditions, drag forceis the dominant force causing the blades to rotate. With increasing RPMthe magnitude of the airspeed due to rotation vectors increase. Theresult is that the magnitude of resultant air flow (29) and drag force(30) decrease and the magnitude of resultant air flow (28) and liftforce (32) increase. At higher RPM's, lift force (32) will be thedominant force causing the blades to rotate.

It is noted that in the following discussions data is presented that wasobtained from measurements made in a wind tunnel at wind speeds ofapproximately 7 MPH. These measurements are very noisy. For clarity, thedata has been averaged and smoothed to a thin line when presented ingraphical form.

FIG. 6 illustrates the transitions that occur between lift and dragdominated regions of operation. RPM data was taken on a wind poweredalternator as in FIG. 1 in a wind tunnel at approximately 7 mph. Whenthe load resistance is low, the relatively large back EMF in thealternator slows the alternator down resulting in lower RPM. When theload resistance is high, the alternator spins more freely resulting inhigher RPM's. The solid line shows RPM data taken starting with a 20 ohmload and gradually increasing the load resistance to 200 ohms. In theregion labeled (33), as the load resistance is gradually increased from20 ohms, the RPM also gradually increases. The drag force shown in FIG.5 is dominant in this region. In the region labeled (34) the lift forceshown in FIG. 5 becomes comparable to the drag force resulting in a morerapid increase in RPM as the load resistance is increased. Finally, inregion (35), the lift force dominates.

Continuing to refer to FIG. 6, the dotted line graph shows RPM vs loadresistance as the load resistance is reduced from 200 ohms. At 200 ohms,the lift force is dominant and the RPM is high. As the load resistanceis decreased, the region where the lift force is dominant (36) can beseen to extend to a lower load resistances than region (35), followed bya transition region (37) to a region (38) where the drag force is againdominant. Lift dominant region (36) is extended since once in lift modethe wind powered alternator is ‘making its own wind’ and can use its ownwind to remain in lift mode at lower load resistances. In the regionlabeled (42), for the same load resistance, there are two possible RPMvalues. As discussed next, it is always desirable to operate at thehigher RPM value.

FIG. 7 shows output power data from the same test of the wind poweredalternator. Again, the dotted line represents output power as the loadresistance is decreased gradually from 200 ohms where the lift force inFIG. 5 is dominant. As with the RPM data, the lift mode region whenstarting at high load resistance (39) is extended compared to the liftmode region when starting at low impedance (40). In the region labeled(41), for a given load resistance, there are two possible output powers.To maximize power production it is desirable to keep the system'soperating point on the dotted line.

FIG. 8 shows a wind powered alternator with the simplified rotor as inFIG. 3 but using traditional Lenz style blades (51). The height of theblade is given by h. The diameter D, chord length C_(L), cup radius r,attack angle θ, and chord distance C_(d) from center at the verticalmidpoint of the blade are is as in FIG. 4 and obey the relationship:r/D<C_(L)/D<1. The chord distance C_(d) and the attack angle θ areconstant. The chart (53) defines the blade parameters at a distanceabove and below the vertical midpoint of the blade for a generalizedimplementation of the design. The chart (50) details the bladeparameters at elevations above and below the vertical midpoint of theblade in 20 mm increments for one particular embodiment of the inventionwhere at the vertical midpoint of the blade: D=182.4 mm, C_(L)=68.1 mm,r=18.7 mm, C_(d)=53.5 mm, and θ=7.5 degrees. For this reference design,the blade parameters do not change with distance d from the verticalmidpoint of the blade. The result is that the wingtips/blade tips (52)at the terminal bottom and top ends of each blade 51 has the sameprofile as the vertical center of the blade. The total surface area ofeach individual blade is also shown in the chart (50).

FIG. 9 shows a wind powered alternator with the simplified rotor as inFIG. 3 using blades (56) constructed in accordance with the principlesof the current invention. The height of the blades is also here definedby the letter h. The diameter D, chord length C_(L), cup radius r,attack angle θ, and chord distance C_(d) from center at the verticalmidpoint of the blade are as in FIG. 4 and obey the relationship:r/D<C_(L)/D<1. The chord distance C_(d) and the attack angle θ areconstant. However, the cup radius r and the chord length C_(L) decreaseas the distance from the vertical center of the blade increases. Asshown, in this embodiment of the blades (56), the wingtips (57) at theterminal bottom and top ends of each blade (56) are substantiallysmaller than the wingtips (52) in FIG. 8. This results in a reduction oflosses due to turbulence and also a reduction in noise due toturbulence. The chart (58) defines the blade parameters at a distanceabove and below the vertical midpoint of the blade for a generalizedimplementation of an embodiment of the invention. The chord length C_(L)and the cup radius r at a distance d from the vertical center of theblade are given by two simple, second order polynomials. Thecoefficients j_(CL) and k_(CL) define the variation in chord lengthC_(L) as d increases. Similarly, the coefficients j_(r) and k_(r) definethe variation in cup radius r as d increases. D also varies withdistance from the vertical center of the blade, but it is a dependentvariable and is fully defined by the cup radius r and the cord distanceC_(d) from center at any particular distance d from the vertical centerof the blade. However, it also can be described by a second orderpolynomial and its equation is included for completeness. To insure thatthe cup radius and cord length continuously decrease as d increases, thej and k coefficients in the table (58) must satisfy the followingcondition: 2*j*d+k<=0.

As depicted in FIG. 9, the blade (56) is symmetrical above and below thevertical center of the blade. The curvature above and below the verticalcenter could also be different. If using a polynomial description ofsuch blades, this would mean the coefficients above and below thevertical center of the blade would be different.

The chart (55) details the blade (56) parameters at elevations above andbelow the vertical midpoint of the blade in 20 mm increments where, atthe vertical midpoint of the blade: D=182.4 mm, C_(L)=68.1 mm, r=18.7mm, C_(d)=53.5 mm, and θ=7.5 degrees. These are the same parameters asin the chart (50) in FIG. 8 which means the center cross section forthese two wind powered alternators would be the same. It also means thatthe startup properties will be similar since the distance of the bladefrom center is the same. The height h for blades (57) is chosen so thatthe surface area of each blade 57 in table (55) is roughly similar tothe surface area of the blades (51) shown in the table (50) of FIG. 8.Therefore, the amount of material needed to make each blade is alsogenerally similar. The design coefficients for the blade (57) in table(55) are: j_(CL)=−0.00725, k_(CL)=0, j_(r)=−0.00725, k_(r)=0.

FIG. 10 shows a wind powered alternator with the simplified rotor as inFIG. 3 using blades (60) also constructed in accordance with theprinciples of the current invention. The height of the blades is alsohere defined by the letter h. The diameter D, chord length C_(L), cupradius r, attack angle θ, and chord distance C_(d) from center at thevertical midpoint of the blade are as in FIG. 4 and obey therelationship: r/D<C_(L)/D<1. However, in this embodiment the cup radiusr, the chord length C_(L), and the cord distance C_(L) from center alldecrease as the distance d from the vertical center of the bladeincreases. As shown, in this embodiment of the blades (60), the wingtips(61) at the terminal bottom and top ends of each blade are substantiallysmaller than the wingtips (52) in FIG. 8. This results in a reduction oflosses due to turbulence and also a reduction in noise due toturbulence. Additionally, the wingtips (61) are also closer to thecenter of rotation which reduces their air speed due to rotation,further reducing turbulence and noise.

The chart (62) defines the blade (60) parameters at a distance d aboveand below the vertical midpoint of the blade (60) for the preferredembodiment of the invention. The chord length C_(L), the cup radius r,and the cord distance C_(d) from center at a distance d from thevertical center of the blade (60) are given by three simple, secondorder polynomials. The coefficients j_(CL) and k_(CL) define thevariation in chord length C_(L) as d increases. Similarly, thecoefficients j_(r) and k_(r) define the variation in cup radius r as dincreases. Similarly, the coefficients j_(Cd) and k_(Cd) define thevariation in chord distance C_(d) from center as d increases. D alsovaries with distance d from the vertical center of the blade, but it isa dependent variable and is fully defined by the cup radius r and thecord distance C_(d) from center at any particular distance d from thevertical center of the blade. However, it also can be described by asecond order polynomial and its equation is included for completeness.To insure that the cup radius r, cord length C_(L), and cord distanceC_(d) from center continuously decrease as d increases, the j and kcoefficients in the table (62) must satisfy the following condition:2*j*d+k<=0. As shown in table (63), the attack angle θ also decreasenear the tips (61) of the blades (60) which further reduces losses andnoise due to turbulence.

As depicted in FIG. 10, the blade (60) is symmetrical above and belowthe vertical center of the blade. The curvature above and below thevertical center could also be different. If using a polynomialdescription of such blades (60), this would mean the coefficients aboveand below center would be different.

The chart (63) details the blade (60) parameters at elevations above andbelow the vertical midpoint of the blade in 20 mm increments where, atthe vertical midpoint of the blade: D=182.4 mm, C_(L)=68.1 mm, r=18.7mm, C_(d)=53.5 mm, and θ=7.5 degrees. These are the same parameters asin the chart (50) in FIG. 8 and chart (55) in FIG. 9 which means thecenter cross section for these three wind powered alternators would bethe same. It also means that the startup properties will be similarsince the distance of the blade from center is the same at the verticalcenter of the blade. However, since the distance of the cord C_(d) fromcenter decreases as d increases, it means portions of the blade (60) arecloser to the center of rotation as compared to the blades in FIGS. 8and 9. This results in higher angular velocities and more powergeneration at a given wind speed once the stationary moment of inertiaand friction is overcome. The height h for blades (60) is chosen so thatthe surface area thereof, and hence each blade depicted in tables (50),(55), and (63), are roughly similar. Therefore, the amount of materialneeded to make each of these blades is also roughly similar. The designcoefficients for the blade in table (63) are: j_(CL)=−0.00725, k_(CL)=0,j_(r)=−0.00725, k_(r)=0, j_(Cd)=−0.00475, k_(Cd)=0. The coefficients forthe cord length C_(L) and cup radius r are the same as those used intable (55) of FIG. 9. The result is that the blades (60) of FIG. 10 havea similar appearance to the blades (56) of FIG. 9, but curve inwardstoward the center of rotation as the distance d from the verticalmidpoint of the blade increases.

Samples of the blades described in tables (50), (55), and (63) werefabricated and their performance was compared in a wind tunnel at a windspeed of approximately 7 MPH. As in FIG. 6 and FIG. 7, RPM and powerdelivered to a load resistance were measured as the load resistance wasincreased and decreased. This data was then used to calculate afull-system power coefficient (Cp), which is the ratio of the powerdelivered to the load resistance to the total wind power flowing intothe turbine blades, versus TSR. As those skilled in the art willunderstand, the power available (Pw) from the wind is directlyproportional to the swept area (A) of the turbine blades and the windspeed (V) to the third power: Pw=B*(q*A*V{circumflex over ( )}3)/2 whereq is the air density and assumed to be 1.2 kg/m{circumflex over ( )}3for these discussions and B is the Betz limit. The swept areas for thethree fabricated blade designs are included in tables (50), (55), and(63). TSR's were calculated at the maximum diameter of the wind turbineblades.

FIG. 11 is a graph comparing Cp versus TSR for the embodiment of theinvention shown in FIG. 9 versus the blades shown in FIG. 8. Allmeasurements were made using the same alternator and at the same windspeed. Measurements were made starting with the load resistance open toachieve maximum RPM and then the load resistance was decreased down to50 ohms. Decreasing the load resistance from a high impedance to a lowimpedance insures the operating point is always on the higher side ofthe hysteresis curve. As can be seen in FIG. 11, the maximum Cp for thetwo blades is similar, but the peak is wider for the blade as in FIG. 9.For any given TSR, the Cp for the blades of FIG. 9 is either similar toor greater than the Cp for the blades of FIG. 8. In a typicalapplication, wind speed will vary from moment to moment and the inertiaof the wind powered alternator will cause the TSR to vary also. A widerCp versus TSR curve will perform better under these conditions so, for asimilar amount of material, the blades of FIG. 9 will outperform theblades of FIG. 8 in most applications.

FIG. 12 is a graph comparing Cp versus TSR for the embodiment of theinvention shown in FIG. 10 versus the blades shown in FIG. 8. Allmeasurements were made using the same alternator and at the same windspeed. Measurements were made starting with the load resistance open toachieve maximum RPM and then the load resistance was decreased down to60 ohms. As can be seen in FIG. 12, the maximum Cp for the blades ofFIG. 10 is always higher than the Cp for the blades of FIG. 8. The curvefor the blades of FIG. 10 is also wider. As discussed above, for asimilar amount of material, the blades of FIG. 10 will outperform theblades of FIG. 8 in most applications.

FIG. 13 shows the output power of the blades shown in FIG. 8 compared tothe blades shown in FIG. 9 versus load resistance. As discussedpreviously for FIG. 7, both blades show regions where for the same loadresistance there are two possible output powers where the higher powercan be achieved when the blade is ‘making its own wind’. As can be seenin FIG. 13, the blades as shown in FIG. 9 outperform the blades shown inFIG. 8.

FIG. 14 shows the output power of the blades shown in FIG. 8 compared tothe blades shown in FIG. 10 versus load resistance. As discussedpreviously for FIG. 7, both blades show regions where for the same loadresistance there are two possible output powers where the higher powercan be achieved when the blades are ‘making its own wind’. It can beseen in FIG. 14 that the blades as shown in FIG. 10 outperform theblades shown in FIG. 8 only when they are on the upper curve where theyare ‘making their own wind’. If on the lower curve the blades from FIG.10 underperform the blades shown in FIG. 8. To optimize performance whenusing the blades as shown in FIG. 10, it is important to make sure theoperating point is on the upper curve whenever possible.

FIG. 15 repeats the power versus load impedance curve for the blades asshown in FIG. 10 and illustrates a method to maintain the optimumoperating point. Assume an 80 ohm load impedance and that the windpowered alternator is operating at point A. There is a higher operatingpoint available at point B. The higher operating point can be reached byincreasing the load impedance to more than 170 ohms which will move theoperating point along the lower curve as illustrated by trajectory (66)to operating point C. At this point the wind powered alternator ismaking its own wind and the load impedance can be reduced back to 80ohms. The operating point will follow the trajectory illustrated by thetrajectory (68) to the optimal operating point B.

FIG. 16 is a simplified schematic illustrating the use of a wind poweredalternator (69) constructed in accordance with the principles of thepresent invention to charge a rechargeable battery (71). As thosefamiliar with the art with understand, a full wave bridge rectifier (70)converts the alternating current from the wind powered alternator (69)to a DC current that can be used to charge the battery (71). Controllogic (not shown) can connect or disconnect the battery (71), such aswith a load switch (72), in order to optimize the power delivered to thebattery. When it is determined by the control logic that the operatingpoint is on the lower of two possible operating points (e.g. point A ofFIG. 15), the load switch (72) is opened. Without the load connected,the load impedance is high and the alternator RPM will increase (e.g.along trajectory 66 of FIG. 15). When the RPM increases enough that thewind powered alternator is making its own wind (e.g. point C of FIG.15), the load is reconnected and the operating point will move (e.g.along trajectory 68 of FIG. 15) to the higher of the two possibleoperating points (e.g. point B of FIG. 15). While the load switch (72)has disconnected the battery (71), no power is delivered to the battery.It is, therefore, necessary to make sure that the power gained by movingto the higher operating point is not offset by the power lost while thebattery (71) is disconnected. When the battery (71) is disconnected, theRPM of the alternator will start to increase. While RPM is increasing,the momentum of the alternator also increases. This increased momentumrepresents potential energy that can be recovered when the battery (71)is reconnected. As long as the RPM is increasing while the switch (72)is open, there is little loss in the total energy that can be collected.However, if the switch (72) is open long enough, at any given windspeed, the RPM will reach a maximum value and stop increasing. Themomentum will also stop increasing, so there is no further increase inthe potential energy available. Therefore, if the switch (72) is leftopen long enough that the alternator RPM stops increasing, the poweravailable from the wind will be lost and the full power systemcoefficient will decrease. One method to avoid this loss is for thecontrol circuit to monitor the RPM while the switch (72) is open andreconnect the battery as soon as the RPM stops increasing. An alternatemethod is to open the switch (72) periodically for a period of time thatis less than three of the alternator's mechanical time constant. At thistime the RPM will have reached 95% of its maximum value. The batteryshould be disconnected often enough to follow the expected variations inthe wind. For the preferred embodiment of the invention, the battery isdisconnected for 3 seconds every 21 seconds.

Referring again to FIG. 16, those skilled in the art will recognize thatwhen the peak voltage output of the alternator (69) is less than thebattery voltage, the bridge rectifier (70) will stop conducting and thuseffectively disconnect the battery (71). This unloads the alternator(69) and allows it to spin freely in winds that are too light togenerate enough power to charge the battery (71) thus providing apleasing visual effect when not generating power.

FIGS. 17a and 17b illustrate another advantage of the preferredembodiment of the invention. If the blades are made from a shinymaterial, there will be specular reflection. It is desirable that thisreflected light directly reflect to the eye (75) of an observer from asmany elevations of the light source as possible. In FIG. 17a , it can beseen that when the sun is at a low elevation (73), sunlight will reflectfrom the blades of the wind powered alternator (51) directly back to theeye (75) of an observer as illustrated by ray (76). However, if the sunis at a higher elevation (74), the reflected ray (77) misses theobserver's eye (75). In the preferred embodiment of the invention shownin FIG. 17b , when the sun is at a low elevation it reflects from theblades of wind powered alternator (60) directly back the observer's eye(75) as illustrated by ray (78), and it also reflects directly back tothe observers eye (75) when the sun is at a higher elevation (74) asillustrated by ray (79).

Referring now to FIG. 1, the blades (1), (2), and (3) are attached tothe rotor (5) below the vertical midpoint of the blades at location(80). At high RPM, there will be centripetal forces on the blades awayfrom the center of rotation. As the distance from mounting location (80)to the top of the blades is longer than the distance to the bottom ofthe blades, the net torque on the blades about location (80) will tendto spread the blade tips at the top of the blades and compress the bladetips at the bottom of the blades. Having the blade mount at a location(80) below the vertical center of the blades means that only onestabilizer (47) is required since stopping the blade tips fromcompressing at the bottom of the blades will also keep the blade tips atthe top of the blades from spreading as long as the blades are strongenough not to bend at high RPM.

FIG. 18 shows a cutaway view of the preferred embodiment of theinvention shown in FIG. 1 with blade (1) removed. A threaded shaft (81)passes through a bottom cover (82), a lower flux plate (83), a lowermagnet holder (84), a stator (85), an upper magnet holder (86), an upperflux plate (87) and an upper cover (88). The threaded portion of shaft(81) attaches to a mounting stake (46). Each magnet holder (84), (86)has openings to retain 4 magnets (90). A locating tab (91) on the topside of rotor (5) engages a slot in upper magnet holder (86). A similartab (not shown) on the lower side of rotor (5) engages a slot in lowermagnet holder (84) to ensure that the magnets in the upper magnet holder(86) are directly above the magnets in the lower magnet holder (84).Upper and lower flux plates (83) (87) are made from a ferromagneticmaterial, preferably steel, and are in direct contact with magnets (90)so as to concentrate the magnet fields lines and maximize the magneticfield strength in the gap between each of the vertically aligned magnetpairs. Shaft (81) is coupled to bottom cover (82) by bearing (92). Asimilar bearing (92) (shown in FIG. 19) couples the shaft (81) to theupper cover (88). The upper and lower covers (88), (82) capture themagnet holders (86), (84) and attach them to rotor (5). As such, therotor (5) is free to rotate around shaft (81) which causes the magnets(90) to also rotate around the shaft (81). The stator (85) is fixed toshaft (81) which does not rotate. Four coils (93) of copper wire areattached to stator (85) and so are also stationary. As the rotor (5)rotates, the magnets (90) rotate past the coils (93) and induce acurrent in each coil. The coils (93) are connected in series and areconnected to circuit board (94) thus supplying power to operate LED (95)and to charge battery (96). In the preferred embodiment, the coils (93)are preferably 470 turns of #30 PN bond #1 MW29-C wire with a 29 mmdiameter and 3 mm thickness. The magnets (90) are preferably 25 mm×6.3mm grade 5 ceramic magnets.

Referring now to FIG. 19, FIG. 20 and FIG. 21, shaft (81) is coupled tothe revolving parts of the VAWT by two bearings (92). The stator (85) isfixedly attached to the shaft (81) and contains four coils (93). Thefour coils (93) are connected in series at locations (112), (113), and(114) (hidden from view). The two remaining wires (101) (102) at theends of the in series coils pass up a slot (103) in shaft (81) andconnect the coils to circuit board (94). The upper end of shaft (81) isattached to ornament platform (89) by screw (104). Wire (105) connectsthe circuit board (94) to positive battery contact (106) and wire (107)connects the circuit board to negative battery contact (108).

The ornament platform (89) is located directly above and in closeproximity to the stator (85). This minimizes the length of shaft (81)which minimizes the distance from the circuit board (94) to the coils(93). The ornament platform (89) provides two posts (116) and a screwhole (117) to locate and attach PCB (94) using screw (119). Ornamentplatform (8) also provides a pocket (115) for battery (96) and two slots(118) for installing positive contact (106) and negative contact (108).Structures (120) and (121) capture springs (97) and (110) and hold themin place. Retaining clips (98) and (109) can slide in radially extendingslots (122) formed on the ornament platform 89 and are pressed radiallyoutward by springs (97) and (110), respectively. Latches (123) on theretaining clips (98) and (109) catch on tabs (not shown) on theunderside of ornament platform (89) to prevent the retaining clips (98)and (109) from overextending. Tabs (100) are provided on the retainingclips (98) and (109) so that the retaining clips can be compressedmanually if the decorative ornament (6) needs to be removed. In FIG. 19,retaining clip (109) is shown in its compressed position which releasesthe decorative ornament (6), whereas retaining clip (98) is shown in theextended position whereby it captures the decorative ornament (6) atcontact point (111).

Decorative ornament (6) rests on ornament platform (89) and encloses andhides from view the battery (96), battery contacts (106) (108), circuitboard (94), retaining clips (98) (109) and springs (97) (110). In apreferred embodiment, the decorative ornament (6) is a decorative hollowglass globe with an opening sized to fit ornament platform (89). A thindiffusing layer (99), preferably a thin layer of white glass, on theinside of the ornament reflects a portion of the light from LED (95) toevenly illuminate decorative ornament (6). The translucence of thediffusing layer (99) is chosen to maximize the light intensity on thesurface of the decorative ornament (6) while remaining opaque enough tohide the structures internal to the ornament. Those skilled in the artwill understand that methods other than a thin white layer of glass canachieve the same effect including, but not limited to, using frostedglass or adding diffusing agents or pigments to the glass. Materialsother than glass could also be used.

Electronics on the circuit board (94) (not shown) control the chargingof the battery and the illumination of the LED. In a preferredembodiment, the LED is illuminated at a first illumination level whendusk is detected. In order to minimize the drain on the battery (96),the illumination level is gradually reduced to a second illuminationlevel. The first illumination level is brighter than the secondillumination level. The transition time from the first illuminationlevel to the second illumination level is chosen so the ornament will bebrighter during the early part of the evening when it is most likely tobe observed and dimmer, and therefore using less power, during lateevening and early morning hours when the ornament is less likely to beobserved. The LED is then turned off at dawn. In this manner, theornament is illuminated from dusk to dawn but can use considerably lesscurrent that if the ornament was illuminated at the first illuminationlevel for the entire night. In a preferred embodiment, the transitiontime from the first illumination level to the second illumination levelis six hours and the first illumination level is eight times the secondillumination level. As there are likely to be days and nights withlittle wind intermixed with days with lots of wind, it is desirable thatthe battery be able to provide illumination for multiple nights withlittle or no wind after being fully charged on a windy day. The firstand second illumination levels and the time to gradually fade from thefirst illumination level to the second illumination level are selectedso that the average current used during the night provides an acceptabletradeoff between brightness and battery life in this situation. In thepreferred embodiment, the first illumination level is set by setting theLED current to 8 mA. Using commonly available LEDs with efficacies of100 lumens/watt or more, this is enough illumination to create apleasing ornament illumination level. The second illumination level isset by setting the current through the LED to 1 mA, which results indimmer illumination of the decorative ornament, but is still adequate.Assuming a linear decrease in illumination, the average current duringthe first six hours of operation is then 4.5 mA. Assuming a 12 hournight, the remaining six hour before dawn will have an average current a1 mA. The average current for a typical 12 hour night would then be 2.75mA, thus consuming 33 mAHr in a single night assuming that only minimalcurrent is used by the electronics. In the preferred embodiment,rechargeable battery (96) is a Lithium Phosphate, 3.2 volt battery witha 400 mAHr capacity, so if the battery is fully charged on a windy dayit will be able to continue illuminating the ornament for at least tennights without any additional wind.

While this invention has been described as having an exemplary design,the present invention may be further modified within the spirit andscope of this disclosure. This application is therefore intended tocover any variations, uses, or adaptations of the invention using itsgeneral principles.

What is claimed is:
 1. A vertical axis wind turbine comprising aplurality of blades adapted to rotate about a vertical axis, whereineach of the blades comprise: a leading cupped section joined to alagging airfoil section, wherein the leading cup section is defined by acup radius r and the lagging airfoil section is defined by an airfoilchord length C_(L); wherein the leading cupped section and laggingairfoil section extend vertically a distance h between terminal bottomand top ends; and, wherein the cup radius r and chord length C_(L) bothdecrease towards the terminal bottom and top ends of the blade.
 2. Thevertical axis wind turbine of claim 1 wherein the cup radius r and chordlength C_(L) both decrease towards the terminal bottom and top ends ofthe blade starting from a vertical midpoint between the terminal bottomand top ends.
 3. The vertical axis wind turbine of claim 1 wherein theairfoil section is located a radial distance C_(d) from the verticalaxis and wherein the radial distance C_(d) decreases towards theterminal bottom and top ends of the blade starting form a verticalmidpoint between the terminal bottom and top ends.
 4. The vertical axiswind turbine of claim 1 wherein the airfoil section is located a radialdistance C_(d) from the vertical axis and wherein the radial distanceC_(d) decreases towards the terminal bottom and top ends of the blade.5. The vertical axis wind turbine of claim 4 wherein the leading cuppedsection extends between an outermost edge and an inner area, wherein theinner area is joined with the airfoil section and the outermost edgetraverses along an arcuate path defined by a diameter D as the bladesrotate about the vertical axis.
 6. The vertical axis wind turbine ofclaim 5 wherein r/D<C_(L)/D<1.
 7. The vertical axis wind turbine ofclaim 4 wherein the blades are coupled to an alternator adapted toproduce electric power.
 8. The vertical axis wind turbine of claim 4wherein the blades are formed of sheet material.
 9. The vertical axiswind turbine of claim 1 wherein the leading cupped section extendsbetween an outermost edge and an inner area, wherein the inner area isjoined with the airfoil section and the outermost edge traverses alongan arcuate path defined by a diameter D as the blades rotate about thevertical axis.
 10. The vertical axis wind turbine of claim 9 whereinr/D<C_(L)/D<1.
 11. The vertical axis wind turbine of claim 1 wherein theblades are coupled to an alternator adapted to produce electric power.12. The vertical axis wind turbine of claim 1 wherein the blades arecoupled to an alternator adapted to produce electric power and a lightemitting device is centrally located between the plurality of blades andis powered by the alternator.
 13. The vertical axis wind turbine ofclaim 1 wherein the blades are formed of sheet material.
 14. Thevertical axis wind turbine of claim 1 wherein the blades are coupled toan alternator adapted to produce electric power and the alternator isselectively connectable to a load through a load switch and furtherwherein, when an output of the alternator is determined to be on a lowerpower of two available operating points, the load is disconnected fromthe alternator and, after the blades and alternator gain momentum, theload is again connected to the alternator resulting in operation at thehigher of the two operating points.
 15. The vertical axis wind turbineof claim 1 wherein the blades are coupled to an alternator adapted toproduce electric power and the alternator is selectively connectable toa battery wherein, when the wind speed is too low to produce enoughpower to charge the battery, the load is disconnected from thealternator and the blades are allowed to spin freely.
 16. The verticalaxis wind turbine of claim 1 wherein the blades are secured to eachother at their terminal bottom end.
 17. The vertical axis wind turbineof claim 1 wherein the blades are coupled to a rotor of an alternatoradapted to produce electric power, wherein the blades are attached tothe rotor below a vertical midpoint between the bottom and top terminalends of the blades and wherein the blades are secured to each other attheir terminal bottom end.
 18. A vertical axis wind turbine comprising aplurality of blades adapted to rotate about a vertical axis, whereineach of the blades comprise: a leading cupped section joined to alagging airfoil section, wherein the leading cup section is defined by acup radius r and the lagging airfoil section is defined by an airfoilchord length C_(L); wherein the leading cupped section and laggingairfoil section extend vertically a distance h between terminal bottomand top ends; and, wherein the airfoil section is located a radialdistance C_(d) from the vertical axis and wherein the radial distanceC_(d) decreases towards the terminal bottom and top ends of the blade.19. The vertical axis wind turbine of claim 18 wherein the radialdistance C_(d) decreases towards the terminal bottom and top ends of theblade starting form a vertical midpoint between the terminal bottom andtop ends.
 20. The vertical axis wind turbine of claim 18 wherein theblades are coupled to an alternator adapted to produce electric powerand the alternator is selectively connectable to a load through a loadswitch and further wherein, when an output of the alternator isdetermined to be on a lower power of two available operating points, theload is disconnected from the alternator and, after the blades andalternator gain momentum, the load is again connected to the alternatorresulting in operation at the higher of the two operating points. 21.The vertical axis wind turbine of claim 18 wherein the blades aresecured to one each other at their terminal bottom.
 22. The verticalaxis wind turbine of claim 18 wherein the leading cupped section extendsbetween an outermost edge and an inner area, wherein the inner area isjoined with the airfoil section and the outermost edge traverses alongan arcuate path defined by a diameter D as the blades rotate about thevertical axis.
 23. The vertical axis wind turbine of claim 22 whereinr/D<C_(L)/D<1.
 24. The vertical axis wind turbine of claim 18 whereinthe blades are coupled to an alternator adapted to produce electricpower.
 25. The vertical axis wind turbine of claim 18 wherein the bladesare coupled to an alternator adapted to produce electric power and alight emitting device is centrally located between the plurality ofblades and is powered by the alternator.
 26. The vertical axis windturbine of claim 18 wherein the blades are formed of sheet material. 27.The vertical axis wind turbine of claim 18 wherein the blades arecoupled to a rotor of an alternator adapted to produce electric power,wherein the blades are attached to the rotor below a vertical midpointbetween the bottom and top terminal ends of the blades and wherein theblades are secured to each other at their terminal bottom end.
 28. Thevertical axis wind turbine of claim 18 wherein the blades are coupled toan alternator adapted to produce electric power and the alternator isselectively connectable to a battery wherein, when the wind speed is toolow to produce enough power to charge the battery, the load isdisconnected from the alternator and the blades are allowed to spinfreely.